SELECT DATENAME(MONTH,datetimeOpened)AS PerMonth,
COUNT(fldIWfId) AS Tickets,
OrganizationfldName AS Customer
FROM mytable
WHERE datetimeOpened > dateadd(year, -1, GETDATE())
GROUP by DATENAME(MONTH,datetimeOpened), OrganizationfldName,
Order BY PerMonth desc